Owl Monkeys are Among the Best Fathers and Faithful Mates

Owl monkeys are among the best fathers and faithful mates in the world. This is according to a study that also found a strong link between fidelity and the quality of child care. Researchers from the University of Pennsylvania found that all the male and female owl monkeys that cared for the young were the infants’ biological parents, suggesting the species never cheated. True monogamy is rare in the animal kingdom. Even in species that appear to mate for life, tests have revealed cheating is common place.

This results come from a long term study that covers a period of 18 years in the Chaco Region of Argentina. Previous research found that male and female owl monkeys form strong pair-bonds. Males contribute significantly to raising young by carrying them on their bodies, playing with them and feeding them solid foods. The investigation of 35 offspring born to 17 owl monkey pairs turned up no evidence of cheating.

The investigation of 35 offspring born to 17 owl monkey pairs turned up no evidence of cheating.

These findings came about as researchers paired behavioral field observations with genetic tests. Scientist wanted to see whether the ‘social’ mothers and fathers of infant monkeys were the biological parents. They collected samples from 128 individual monkeys living in 29 groups or as solitary ‘floaters.’ This set included genetic samples from 35 infants born to 17 reproducing pairs. They examined 14 different regions of the genome, the analysis strongly suggested owl monkeys were completely faithful; there was no evidence of extra-pair paternity.

Map showing the Chaco region and the general study area.

The Gran Chaco is a sparsely populated, hot and semi-arid lowland natural region of the Río de la Plata basin, divided among eastern Bolivia, Paraguay, northern Argentina and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul, where it is connected with the Pantanal region. This land is sometimes called the Chaco Plain.

In the 18 years of the Owl Monkey Project in Argentina, we never witnessed a little sneaky copulation with a neighbor, or that one partner dashed off for some time. True genetic monogamy is very rare. We would not have been surprised if there had been at least one non-pair infant, but there were none. Our study is the first of any primate species, and only the fourth for a pair-living mammal, to show genetic monogamy, or real faithfulness, between partners said associate Professor Eduardo Fernandez-Duque, of the Department of Anthropology at Pennsylvania State University. According to researchers, no other robust study of primates has demonstrated genetic monogamy.